This invention relates to integrated processing of residual oil by residual oil supercritical extraction (ROSE), asphaltene gasification, gas cleaning, and generation of power, steam, hydrogen and/or synthesis gas, and more particularly to ROSE integration with gasification and combined cycle power and/or steam generation using high-level heat exchange to eliminate the need for a fired heater and/or steam generator supporting the ROSE unit.
The process of gasification, gas cleaning, and combined-cycle power generation is known as integrated gasification combined cycle or IGCC. IGCC disposes of residual oil, asphaltenes, or other fuels with impurities to produce power, and can also provide steam, synthesis gas and/or hydrogen. Heat may be recovered from the gasifier effluent in a high pressure boiler, and after treatment to remove soot, metals, acid gases, and other impurities as needed, the gasifier effluent is used as fuel gas in a combustion turbine to generate electrical power. Additional heat is recovered from the hot turbine exhaust in another high pressure boiler (known as a heat recovery steam generator or HRSG), and high pressure steam from both the gasifier and turbine exhaust boilers may be fed to steam turbines to generate additional electricity. Alternatively, all or part of the cleaned gasifier effluent can be used locally or exported as fuel gas or synthesis gas, or used to produce hydrogen, e.g. by shift conversion.
ROSE is typically used to recover deasphalted oil (DAO) from a residual oil (resid) for further treatment, typically catalytic cracking, leaving an asphaltene stream having minimal value. ROSE consumes large quantities of process heat, with significant high-level heat loads at temperatures ranging as high as 260° C. to 425° C., depending on the solvent and operating conditions. A dedicated fired heater typically provides the heat loads. The fired heater is expensive, requires operator attention, requires costly fuel, takes up valuable area in an industrial complex, and constitutes a source of air pollution.
U.S. Pat. No. 6,241,874 to Wallace et al integrates solvent deasphalting with gasification of asphaltenes to syngas using low-level heat from the gasification to recover solvent in the deasphalting unit. Sensible heat is recovered from the synthesis gas to provide the low level heat for separating and recovering solvent from the DAO-solvent mixture in the deasphalting unit. The synthesis gas is supplied directly to a heat exchanger for one separation column in the deasphalting unit, and low pressure steam is supplied to another separation column.
Other U.S. patents of interest to the present invention include: U.S. Pat. Nos. 5,976,361 and 6,274,032 to Hood et al; U.S. Pat. No. 5,911,875 to Hervish et al; U.S. Pat. No. 5,466,365 to Savastano et al; U.S. Pat. No. 5,242,578 to Taylor et al; U.S. Pat. No. 5,192,421 to Audeh et al; U.S. Pat. No. 5,000,838 to Bartilucci et al; U.S. Pat. No. 4,536,283 to Davis; U.S. Pat. No. 4,354,928 to Audeh et al; and U.S. Pat. No. 4,125,458 to Bushnell. All patents and publications mentioned herein are hereby incorporated by reference in their entirety.